Hydrological and Hydraulic Studies

GBMc & Associates have completed numerous hydrological and hydraulic studies for a wide range of applications. Many studies have been completed in support of TMDL and waste load allocations or for flow analysis. Projects often include dye tracer studies to determine time of travel, low and high (flood) flow modeling studies (including HEC-RAS analysis) and direct in-stream measurement of flow using the velocity area method. GBMc scientists and engineers routinely utilize hydrology models including HydroCad and TR55 to determine storm water run-off volume, velocities and time of travel. This data is used in an array of projects including water quality modeling, culvert sizing and design and pond sizing/capacity studies. On several occasions GBMc & Associates have calculated new regulatory low flows (7Q10, 7Q2, etc) for permittees resulting in increases to stream background flows and associated allowable increases in pollutant loading to the receiving stream. Several of our past and current projects include continuous level monitoring equipment installed in stream channels to provide flow estimates using rating curves. GBMc staff has typically designed these studies and installed and maintained the equipment on these projects. GBMc & Associates has a long-time relationship working with state, USGS, and EPA Environmental Quality staff on hydrological and other water quality issues.